Revista de Ciencias

Encapsulation of the Piperine Present in Piper tuberculatum Species Using Multilamellar Vesicles and Determination of its Antioxidant Power

Abstract The piperine is an alkaloid present in the vegetal species pipilongo (Piper tuberculatum). Antioxidant properties are associated to this plant. It was encapsulated in multilamellar vesicles (MLV). For that, the validation of the extraction methodology through calibration curves of standard piperine by high resolution liquid chromatography (HPLC) was performed, using a column of C18, mobile phase MetOH: H2O (70:30) and detected by UV to 340nm with a fluency rate of 0.7 mL/ min. The lineal and non-lineal ranges were found between 1 and 300 ppm, with R2 of 0.995. During the extraction of the pipilongo fruit, the effect of two factors, solvents and ultrasound power, was studied, for the optimization of conditions and higher extraction of piperine in pipilongo. The maximum concentration of piperine (246.50 ppm) was found, using ethanol as extraction solvent. The piperine was isolated from its extract, using a solution of KOH with 10 % ethanol. It was purified and characterized by melting point, IR, GC-MS y RMN 1H. Once the extract was obtained, it was proceeded to the formation of liposomes. The phosphatidylcholine and cholesterol vesicles were prepared with extract and with piperine at different concentrations and hydrated with buffer pH 7.40. The average size of the particles formed, measured by dynamic light scattering (DLS), was in a range of 299.7-531.9 nm. For the study of antioxidant activity, a solution of DPPH 0.2 mM was prepared and a reaction was carried out with the extract and piperine liposomes and their corresponding free forms. The IC50 calculated for the extract and piperine were 2.8±0.2 and 21333±1499 ppm, respectively. These values of IC50 were compared against a standard of reference Quercetin, prepared under the same conditions. The test with DPPH showed that the released form possesses greater antioxidant activity while in encapsulation form, it attenuates and stabilizes this capacity.

Resumen La piperina, alcaloide presente en la especie vegetal pipilongo (Piper tuberculatum) a la cual se le asocian propiedades antioxidantes, fue encapsulada en vesículas multilamelares (MLV). Para ello se realizó la validación de la metodología de extracción a través de curvas de calibración de piperina estándar por cromatografía líquida de alta resolución (HPLC) utilizando una columna C18, fase móvil MetOH:H2O (70:30) y detectada por UV a 340 nm con una tasa de flujo de 0.7 mL/min. El rango lineal y linealidad fueron halladas entre 1 a 300 ppm, con R2 de 0.995. En la extracción del fruto de pipilongo se estudió el efecto de dos factores, disolventes y potencia de ultrasonido, para la optimización de condiciones y mayor extracción de piperina en pipilongo. La máxima concentración de piperina (246.50 ppm) fue encontrada en las condiciones de ultrasonido (US 20 KHz a 175W, 40 min) utilizando etanol como disolvente de extracción. Del extracto, se aisló la piperina utilizando una solución de KOH 10% etanólico. Fue purificada y caracterizada mediante punto de fusión, IR, GC-MS y RMN 1H. Una vez obtenido el extracto, se procedió a la formación de liposomas. Las vesículas de fosfatidilcolina y colesterol fueron preparadas con extracto y con piperina a diferentes concentraciones e hidratadas con buffer PBS a pH 7.40. El tamaño promedio de las partículas formadas, medido por dispersión de luz dinámica (DLS), estuvo en un rango de 299.7-531.9 nm. Para el estudio de la actividad antioxidante, se preparó una solución de DPPH 0.2 mM y se llevó a reacción con los liposomas de extracto y de piperina y sus correspondientes formas libres durante 60 min, medidos a 520 nm. El IC50 calculado para el extracto y la piperina fueron 2.8±0.2 y 21333±1499 ppm, respectivamente. Estos valores de IC50 fueron comparados frente a un estándar de referencia preparado bajo las mismas condiciones, quercetina (IC50 2.5±0.1 ppm). El ensayo con DPPH mostró que la forma liberada posee mayor actividad antioxidante mientras que en la encapsulación atenúa y estabiliza esta capacidad.

Aquatic insects associated with roots of Eichhornia crassipes (Mart) Solms in wetlands of Atrato River, Chocó - Colombia

Abstract Aquatic macrophytes play an important role in lentic systems, as they constitute a particular habitat for various groups of aquatic insects and play an important role in the structuring of their communities. The objective of this study was to characterize the community of aquatic insects associated to Eichhornia crassipes (Mart) Solms in five swamps of the middle and lower basins of the Atrato River, Chocó-Colombia. During two months aquatic insects were collected, using a quadrant of one m2, with a mesh of 0.5 mm, with three replicates per swamp. Simultaneously some physical, chemical and hydrological variables were measured (dissolved oxygen, pH, water temperature, electrical conductivity, alkalinity, total dissolved solids, transparency and depth). The community was composed of 6 orders, 18 families and 24 genera. The most abundant order was Coleoptera (39.81%), standing out the Gyrinidae family with the genus Hydrocanthus; while the greatest taxonomic richness was for dipterans with 7 genera, among which Ablabesmyia stands out. The diversity index presented an average of 1.17 bits/ind ± 0.47, while the average dominance was 0.54 ± 0.20. The most abundant functional groups were predators and collectors, which accounted for 99.04% of the individuals, predominating Hydrocanthus (Gyrinidae) and Callibaetis (Baetidae) respectively. The physicochemical variables did not show significant differences between samples and there were strong associations between the aquatic entomofauna and the analyzed abiotic variables.

Resumen Las macrófitas acuáticas desempeñan un importante rol en los sistemas lénticos, al constituir un hábitat particular para varios grupos de insectos acuáticos y jugar un papel importante en la estructuración de sus comunidades. El objetivo de este estudio fue caracterizar la comunidad de insectos acuáticos asociados a Eichhornia crassipes (Mart) Solms en cinco ciénagas de la cuenca media y baja del río Atrato, Chocó-Colombia. Durante dos meses se hicieron colectas de insectos acuáticos, utilizando un cuadrante de un m2, dotado de una malla de 0,5 mm, con tres replicas por ciénaga. Simultáneamente se midieron algunas variables físicas, químicas e hidrológicas (oxígeno disuelto, pH, temperatura del agua, Conductividad eléctrica, alcalinidad, sólidos totales disueltos, transparencia y profundidad). La comunidad estuvo compuesta por 6 órdenes, 18 familias y 24 géneros. El orden más abundante fue Coleoptera (39,81%), sobresaliendo la familia Gyrinidae con el género Hydrocanthus; mientras que la mayor riqueza taxonómica fue para los dípteros con 7 géneros, entre los que destaca Ablabesmyia. El índice de diversidad presentó un promedio de 1,17 bits/ind ± 0,47, mientras que el promedio de la dominancia fue de 0,54 ± 0,20. Los grupos funcionales de mayor abundancia fueron los predadores y colectores que representaron el 99,04% de los individuos, predominando Hydrocanthus (Gyrinidae) y Callibaetis (Baetidae) respectivamente. Las variables fisicoquímicas no mostraron diferencias significativas entre muestreos y existieron fuertes asociaciones entre la entomofauna acuática y las variables abióticas analizadas.

Dependence with the Temperature of the Defect Modes in a One-dimensional Photonic Crystal

Resumen En el presente trabajo calculamos la dependencia con la temperatura de los modos localizados en espectro de transmitancia para un Cristal fotónico unidimensional con dos defectos. La estructura considerada está formada por materiales de TiO2 y SiO2. Haciendo uso del método de transferencia matricial para el caso de polarización TE con incidencia normal, se encuentra la presencia de dos modos defecto alrededor de la longitud de onda del diseño λ0. Al tener en cuenta la dependencia con la temperatura del índice de refracción y de los espesores del cristal, se muestra un corrimiento a longitudes de onda largas de los modos defecto a medida que se incrementa la temperatura.

Abstract In the present work we calculate the dependence with the temperature of the modes located in the transmittance spectrum for a one-dimensional photonic crystal with two defects. The structure in question is composed of materials of TiO2 and SiO2 Making use of transfer matrix method for the TE polarization case with a normal incidence, we find the presence of two defect modes around the design wavelength λ0. By taking into account the dependence on the temperature of the refractive index and the thickness of the crystal, a shift to long wavelengths of the defect modes is shown as the temperature increased.

Identification of a Hopf bifurcation with or without parameters

Resumen En este trabajo se presenta los lineamientos teóricos que identifica la existencia de una bifurcación genérica de Hopf, con o sin parámetros, a través de un punto o una línea de puntos de equilibrio para un sistema dinámico continúo. Con estos lineamientos definidos, se analiza la bifurcación de Hopf sin parámetros a través del estudio de contornos viscosos para un sistema de ecuaciones diferenciales parciales conformado por un término de reacción - difusión; con condición inicial constante a trozos y una línea de puntos de equilibrio que presenta un par de valores propios complejos conjugados con parte real nula en su linealización a medida que se aproxima al origen. En condiciones adecuadas, se distinguen dos casos para este tipo de bifurcación genérica de Hopf sin parámetros: hiperbólica y elíptica, genéricas en el sentido que es una bifurcación controlada en una línea de puntos de equilibrio.

Abstract In this paper, we present the theoretical guidelines that identify the presence of a generic Hopf bifurcation, with or without parameters, through a point or a line of equilibrium points for a continuous dynamic system. With these defined guidelines, the Hopf bifurcation without parameters is analyzed through the study of viscous contours for a system of partial differential equations conformed by a reaction-diffusion term; with initial condition constant to pieces and a line of equilibrium points that presents a pair of complex eigenvalues conjugated with null real part in its linearization as it approaches the origin. Under appropriate conditions, two cases are distinguished for this type of generic Hopf bifurcation without parameters: hyperbolic and elliptical, generic in the sense that it is a controlled bifurcation in a line of equilibrium points.

Prevalence and Antimicrobial Susceptibility of Potentially Pathogenic Bacteria and Fungi Isolated from Public Parks of Bogotá, Colombia

Abstract Regular interactions of humans with their environment, animals and different microorganisms as part of everyday routine can cause several infections or diseases that can become a public health problem if these are not properly controlled. It is necessary to identify potentially pathogenic bacteria (with its antimicrobial resistance) and fungi, and their prevalence in public parks in Bogotá city. Four parks were evaluated, where samples were taken from dog’s feces and hair, recreational items and environmental material, to perform the microorganism’s isolations. The higher prevalence percentages in each sort of sample were for Escherichia coli, Staphylococcus epidermidis, Staphylococcus aureus, Rahnella aquatilis, Penicillium spp, Cladosporium spp. and Mucor spp. and there were pathogenic species like Salmonella enteritidis and Klebsiella pneumoniae. We report a strain of S. aureus with intermediate resistance to vancomycin (VISA) found in recreational items. The higher rates of antibiotics resistance like ampicillin and trimethoprim were found in the isolations from dog’s feces. Some species or genera reported are considerated as opportunistic pathogens; however, these and the pathogenic species reported represent a threat to human health and this is why it is essential to have a personal hygiene plan after stay at a park.

Identification of Phytopathogenic Fungi in Cultivars of the Heliconiaceae Family

Abstract The main pathogens that affect the foliage and floral bracts of Heliconia cultivars in Las Heliconias National Park (Caicedonia, Colombia) were identified. Random samples were taken of foliage and floral bracts presenting symptoms of damage caused by phytopathogenic fungi. The degree of damage was described qualitatively and was correlated with the phytosanitary state of the crop. Reports of the evaluated plants indicated that 75% of the pathogens resided in the foliage and 25% resided in the floral bracts. The statistical analysis determined that the microorganisms Aspergillus sp., Fusarium sp., and Nigrospora sp. appeared equally in the two evaluated organs. The fungal genera found associated with plant sickness symptoms were considered to be phytopathogens. The degree of infection and development of disease varied from moderate lesions to severe infection. Reproductive fungi were present in the different plant organs studied and in organic matter residue in the soil.